In order to determine the correct amount of fuel, the ECM uses the MAP to help determing the amount of intake air flow. To measure the air flow in the intake manifold, the MAFS is used at idle and MAPS is required during accelerating. The MAPS(Manifold Absolute Pressure) calculates the amount of air indirectly as measuring the pressure inside of intake manifold. This system is called a Speed-Density type.MAPS transfers analog output signal which is proportional to the change of intake manifold pressure, then, with this signal and RPM, ECM calculates the amount of intake air flow. The MAPS is mounted on the surge tank to measure the pressure inside of intake manifold, and it consists of a piezo electric element and a hybrid IC which amplifies the output signal from the element. A diaphragm with a piezo electric element is use to convert pressure into voltage. One side of the diaphragm has a chamber with a fixed (absolute) pressure while intake pressure is applied to the other side. As the intake manifold pressure changes, the diaphram moves which changes a voltage output.
If the signal output of MAP sensor is stuck under enable conditions or If the acutal MAP value or lower than calculated(threshold) value for 2 min failure during tip in-out driving, or If there is the signal change over 10% momently without the operation of accel pedal, ECM determines that a fault exists and a DTC is stored.
Item | Detecting Condition | Possible cause | |
DTC Strategy | Case 1 |
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Monitor the MAP sensor's signal |
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Connecting condition
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Open or short to ground in power circuit
•
Open or short to ground in signal circuit
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Faulty TPS
•
Faulty MAPS
•
Faulty ECM |
Case 2 |
•
The MAP reading is compared to expected MAP high and low limits based on engine speed & Throttle Position | ||
Case 3 |
•
This code detects a erratic signal change of the MAP | ||
Enable Conditions | Case 1 |
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No Disabling Fault Present
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Shutdown time > 20 minutes
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Engine running | |
Case 2 |
•
Engine Coolant Temperature ≥ 60℃ (Fully Warmed up state)
•
600rpm < Engine Speed < 3000rpm | ||
Case 3 |
•
Engine running
•
l ΔAPS l < 5%
•
Engine Speed > 800rpm | ||
Threshold value | Case 1 |
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The difference between the signal at key-on and the signal at engine start < 0.5 kPa | |
Case 2 | '- Power Test
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Altitude compensated MAP < Calculated min. MAP data
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Altitude compensated MAP > Calculated max. MAP data - Decelleration Test
•
Altitude compensated MAP < Calculated MAP data | ||
Case 3 |
•
MAP_stable –MAP_current| >10 % | ||
Diagnosis Time | Case 1 |
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For 3 seconds out of 5 seconds | |
Case 2 |
•
Continuous (within 5min.) | ||
Case 3 |
•
- | ||
MIL On Condition |
•
NO MIL ON(DTC only) | ||
Pressure(kPa) | Voltage(V) |
20 | 0.79 |
46.66 | 1.84 |
101.32 | 4.0 |
Fig.1) Normal waveform of MAPS & TPS with acceleration.
Fig.2) Normal data of MAPS at idle.
It is necessary that MAPS should be checked along with TPS. Because the MAP/TPS rationality diagnostic is comprised of two tests. A deceleration test is performed to provide a robust method for detection of an altitude compensated MAP value that is too high for the deceleration condition. The second test compares the altitude compensated MAP value to both high and low limits, dependent upon throttle position and engine speed. When the MAP value is out of the threshold range, the MAP/TPS system is determined to be failed.
